Designating its ongoing probe as a special investigation would put the case at the top of regulator Bafin’s priority list and open the door to more intensive queries.

That would raise the stakes for Germany’s biggest bank, which only last week suspended several currency traders in New York in an internal probe that forms part of an international investigation into alleged manipulation of global currency markets.

Bafin declined to comment. The agency is conducting several parallel probes at Deutsche Bank, including a long-running investigation into the manipulation of benchmark interest rates.

Benchmark foreign exchange rates, or daily fixings, are a cornerstone of global financial markets, used to price trillions of dollars worth of investments and deals and relied upon by companies, investors and central banks.

In any special probe, supervisors would also want to examine chats that allegedly took place on a trading platform used by currency traders and those involved in the Libor interest rate-fixing scandal, Der Spiegel added.

Deutsche Bank declined to comment on the prospect of a special investigation.

It said in a statement it had received requests for information from regulatory authorities that were investigating trading in the foreign exchange market.

“The bank is cooperating with those investigations, and will take disciplinary action with regards to individuals if merited,” it said.

Last year, Britain’s Financial Conduct Authority began a formal investigation into possible manipulation in the $5.3 trillion-a-day global foreign exchange market. The U.S. Justice Department is also engaged in an investigation of possible manipulation of the market, the world’s largest.

Deutsche Bank has been the biggest foreign exchange trader in the world for nine years running, seeing 15.18 percent of global daily turnover in 2013, according to Euromoney magazine.